Useful Tips for Newcomers
All the characters can win easily at the starting difficulty (when played by an experienced player, obviously as a new player you can have struggle with any of them), so try them all and play whichever you like. Only two short-term caveats to that.
You get unlocks for doing runs as each character, which are mainly cards for that character, but there are also a few relics for any character you can unlock, so trying to hit all the unlocks on each character is worth doing. There is also feature unlock that requires you to beat the game once as each of the first three characters. Once you do those though, there is no particular reason to play anything but what you want.
As for tips, a few basic ones. Every act 1 elite and boss punishes you for having low damage, so your first several floors should be focused on doing fights and choosing damage cards. With a few good damage cards, you can start doing elites for relics, which will help the rest of your run.
Once you get your damage in a good place, you can start worrying more about defense and finding a way of scaling into the late game. In general, the path you want to pick is the one with the highest combined total of campfires and elites, since those are the best permanent upgrades to your run, but there are plenty of exceptions and edge cases to that guideline, such as getting to a shop when you have lots of gold.
Lastly, don’t be afraid to skip cards. Once you have a basic deck theme established, you can start skipping cards that don’t fit it. If you are running a Shiv deck in Silent, skip poison cards, for example; making one strategy really strong is typically better than having several weaker strategies.
A smaller deck means you can draw the cards you want more often, and the limited amount of upgraded cards you can get cycle back around more quickly. This means that later in a run, you can skip even cards that are good for your deck because you already have enough of that effect. If you already have five upgraded shiv cards, you may not need a sixth, seventh, and eight card, since you just shuffle and redraw your upgraded cards instead.
However, a deck that is too small can be ruined by enemies that add dazes, wounds, burns, etc. to your deck, and you generally have fewer options and utility than a larger deck. In general, I try to keep my decks between 20-35 cards, depending on the character and build.
My beginner tip would be to play aggressive. Enemies tend to get more powerful (and make you weaker) as the battle goes on, so when you’r’e on the fence as to whether to play a block or an attack card, go for the attack.